Method and apparatus for treating matter in a high-frequency electric field



H. H. s. GRELL EI'AL 2,415,025 METHOD AND APPARATUS EOR TREATING MATTERIN A HIGH FREQUENBY ELECTRIC FIELD Jan. 28, 1947.

Filed April 22, 1943 3 Sheets-Sheet 1 3m 1947'. H. H. s. GRELL ETAL2,415,025

METHOD AND APPARATUS FOR TREATING MATTER IN A HIGH FREQUENCY ELECTRICFIELD 3 Sheets-Sheet 2 Filed April 22, 1943 Patented Jan. 28, 1947UNITED STATES PATENT OFFICE";

METHOD AND APPARATUS FOR TREATING MATTER IN A HIGH-FREQUENCY ELEC- TRICFIELD Herm H. Giodvad Grell, New York, N. Y., and

Harry W. Richards, East Orange, N. J., assignors, by direct and mesneassignments, to The Firestone Tire and Rubber Company, a corporation ofOhio, and The B. F. Goodrich Company, a corporation of New YorkApplication April 22, 1943, Serial No. 484,092

14 Claims.

2 arrangements of electrodes for applying heat to the material undertreatment so that the heating may be either uniform throughout the massor, at the option of the operator, intensified at certain pointstherein.

One of the principal objects of the invention therefore is the provisionof simple and novel When a homogeneous dielectric is placed in a uniformelectrostatic field of high frequency, the material becomes uniformlyheated throughout its mass; any rise in temperature or heating effectincreasing with the frequency and the density of the field. Dielectriclosses thus produced under the influence of high frequency electriccurrents may be used for the treatment of many different kinds ofmaterial. as an example of the use of the present invention, thevulcanization of rubber or other materials will be mentioned herein inconnection with certain specific disclosures, but it is understood thatthe invention in its broader aspects is not sovlimited.

The principle of high frequency electrostatic heating has been advertedto in the patents above mentioned and a widely accepted underlyingtheory may be briefly explained. If the molecules of a substance aredisturbed-for instance rubbed against each other-heat is produced by thefriction, just as heat is produced when two sticks of. wood are rubbedtogether to eventually produce a blaze.

In high frequency electrostatic heating, the electrical energy acts uponthe molecules of the substance within the field influenced by saidenergy causing the molecules to change shape. When the polarity ordirection of the electric field is reversed the molecules assume adifferent shape, and this occurs with each successive reversalofpolarity. When the electrical field is reversed millions of times persecond, the friction created between the molecules quickly produces alarge amount of heat within the substance being treated.

In utilizing electrostatic energy for the production of heat, or othereffects, it is general practice to employ a pair of plate electrodesdisposed one upon each side' of the work and to connect these electrodesto opposite sides of a high frequency source. The present inventioncontemplates the provision of novel forms and Merely forms of electrodesand arrangements of the electrodes and the mass to be treated, wherebyrelative movement between the mass and the electrodes is attained andthe treatment of the mass applied uniformly throughout the mass,concentrated in the outer portions thereof, or

intensified at the central portions of the mass,

as may be desired. By having the material continuously in motionrelative to the electrodes, the time required for heat treating isreduced to a minimum and a uniform finished product is obtained.

A great variety of different materials-solid, liquid, colloidal, orplastic-may be treated within the purview of the present invention. Asan example there may be mentioned the vulcanization of rubber or othermaterials, especially those in which a varying efiect in differentportions of the mass may be desired.

Thus, another more particular object of the invention is to producethrough a. certain arrangement of electrodes or means fortransmittingpulsating current or producing an electrostatic field, an underlyingsection of relatively hard or semi-hard rubber combined with an exteriorsection of softer rubber; for example, in order to assure a more perfectadherence of the coating or insulating covering to the surface of anembedded wire or other metallic core. This form of heat treatment isparticularly adapted to the making of printing press rollers and thelike, wherein the rubber or other roller composition may be made fast tothe metallic core. On the other hand, by a suitable variation in thearrangement of the electrodes or electrostatic field producing elements,the interior portion of the coating material can be made softer than theouter portion, for example, this particular treatment may be applied toinsulated electrical conductors so that the insulation can bereadilystripped from the conductor as when electrical connections are to bemade thereto.

Difliculties which have been experienced heretoiore owing to the lowthermal-conductivity of rubber are entirely eliminated by the presentprocess by means of which uniform and rapid vulcanization may beobtained. It is also possible to vulcanize thick masses of material justas either stationary or in motion. Furthermore, the

drying of ink on freshly printed copy may be effected to prevent offset,as well as any other type of drying, oxidation, curing, polymerizing, oragglomerating of non-metallic materials.

, The invention contemplates in each case the provision of means wherebythe material may be moved with respect to the electrodes, and it alsoembraces means whereby the same effects may be produced by moving theelectrodes with respect to the material being treated.

Other objects and features of novelty will be apparent from thefollowing specification when read in connection with the accompanyingdrawings in which certain embodiments of the invention are illustratedby way of example.

In the drawings:

Figure 1 is a diagram indicating the uniform efiect throughout a mass oftreated material which is obtained by the use of parallel electrodesthroughout the full diameter of the mass, as for example by means of thearrangement shown in Figure 4; a

Figure 2 is a similar diagram showing the efiect of a selectivetreatment of the outer portion of a mass, as for example by the meansshown in Figure Figure 3 is another diagram indicating the effect oftreatment as for example by the means shown in Figure 6, in which theinterior or central portion of the mass receives a more intensetreatment than the outer portions thereof;

Figure 4 is a somewhat diagrammatic showin of an arrangement whereby amass of material may be treated uniformly throughout by means of anelectrostatic field; and in which the mass being treated may be eitherstationary or rotating about the central axis;

Figure 5 is a similar view showing a circular mass of material beingtreated by an electrostatic field in order to effect a change in itsouter portions only, producing a result as indicated in Figure 2;

Figure 6 is a similar view showing a rotating circular mass beingtreated by an electrostatic field so as to obtain an intensified effectat the center of the mass, the product being suggested by the diagram inFigure 3;

Figure 7 is a diagrammatic view, substantially in side elevation, of amass of material being treated by being drawn longitudinally throughsuccessive series of pairs of electrodes arranged in staggeredrelationship so as to produce a product similar to that indicated inFigure 2 and similar to the effect produced by the means shown in Figure5;

Figure 8 is a collective diagrammatic showing of successive transversecross sections taken on lines 8A-8A, 83-83, 80-80, and 8D8D anddesignated respectively by the subordinate figure designations 8A, 8B,8C, and 8D;

Figure '9 is a diagrammatic view substantially in side elevation of amass of material being treated by being drawn longitudinally through aseries of annular electrodes, in order to attain an external or skintreatment, the effect being somewhat similar to that indicated in Figure2; part of the arrangementbeing shown in cross section to indicate theapproximate extent of the electrostatic field between adjacentelectrodes;

Figure 10 is a diagrammatic end view of the device shown in Figure 9;

Figure 11 is a diagrammatic view similar to those shown in Figures 7 and9 but in which the mass of material is being drawn through helicalelectrodes in order to attain a marginal treatment similar to thatsuggested in Figures 10 and.

10 2; part of the arrangement being shown in cross section to indicatethe approximate extent of the electrostatic field between adjacentelectrodesg' Figure 12 is a diagram suggestive of a transverse crosssection through the device shown 15 in Figure 11;

Figure 13 is a collective diagrammatic showing of successive transversecross sections through an arrangement such as illustrated in Figure 7but in which only two oppositely disposed elec- Figures 1, 2, and 3,showing a mass havingan intermediate annular zone treated more intenselythan either the center or outer portions;

Figure 15 is a view similar to Figures 4, 5, and 6 showing means forproducing the effect illustrated in Figure 14; I

' Figure 16 is a diagrammatic view of an apparatus for treating a massof material to attain a product as suggested in Figure 2 and by means ofa device similar to that shown in Figure 5, 40 but in which theelectrodes are rotated around the material;

Figurel'l is a view similar to Figure 14 showing rotatable. electrodesfor attaining an effect as suggested in the diagram of Figure 3 byemploying diametrically oppositely arranged electrodes as in Figure 6;

Figure 18 is a view in side elevation and in somewhat diagrammatic form,showing an arrangement for treating articles arranged in contact with oradjacent to a stationary electrode and having a series of movableelectrodes passed over them;

Figure 19 is an enlarged fragmentary diagrammatic view of the deviceshown in Figure 18; and

Figure 20 is an electrical diagram showing a conventional form ofoscillator circuit for supplying high frequency electric current to theheating electrodes employed in the various embodiments of the presentinvention. 1

Q As exemplifying the reduction of the present invention to practice, agenerally cylindrical elongated mass will be used, and-it will be shownhow such masses may be selectively treated to attain any one of severaldifierent densities of the electrostatic field with respect to the mass,and the resultant selective intensity of heat treatment. These examplesare illustrated diagrammatically in Figures 1, 2, 3, and 14 of thedrawings.

It will be seen that the material or mass ID in Figure 1 comprises anannular body II which, in this particular instance is mounted upon orcarried by a core l2. In an actual embodiment,

* the core l2 may represent an electrical conduc- 7 tor insulated by thebody H-which in that case be employed for example in a printing press orthe like. Obviously, the mass Ill may wholly comprise a dielectric bodyI I without any core l2, within the scope of the invention. In Figure 1the stippling in the diagram indicates the zone treated by theelectrostatic field and it will be seen that this zone comprises theentire cross sectional area of the body II and all parts have been heattreated at the same intensity. 'This uniform effect may be attained forexample by the means diagrammatically illustrated in Figure 4 of thedrawings in which the mass l is mounted between the fiat plateelectrodes 13 and I4 connected respectively to the opposite sides of asource of high frequeny electric current It: by means oi. the wires l6and I1. It will thus be seen that there will be established anelectrostatic field indicated diagrammatically by the lines 20 whichwill extend across the full diameter of the mass Ill which may either bemaintained in a stationary position or rotated between the electrodes.

In Figure 2 of the drawings there is shown a mass ill comprising a bodyll consisting of an untreated central zone l8 and an annular outer zonel9 which has been affected by the heat generated by an electrostaticfield. If this mass I0 is provided with a core l2 as indicated in Figure2, the illustration may exemplifyv an insulated .electrical conductor ofthe type in which the insulation comprising the body I I may be readilystripped from the wire l2 since there is little or no vulcanization ofthe central portion of the covering body to the surface of the wire orconductor l2.

The eiiect suggested in Figure 2 may be attained by means of theapparatus shown diagrammatically in Figure of the drawings in which thebody id is mounted for rotation within the space between the fourelectrodes 22 and 22', 23 and 23'. These electrodes are preferably inthe form of curved plates conforming generally to the curved surface ofthe mass l0; The two electrodes 22 and 22' are connected by means of theconductors 24 to one terminal of a source of high frequency currentsimilar to that indicated at W in Figure 4, and the two electrodes 23and 23' are connected by wires 25 to the opposite terminal. Theelectrodes of the pairs 22 and 23, and 22' and 23' being of oppositeinstantaneous polarity and having portions in rather close prox-' imity,electrostatic fields will be set up such as indicated at 21 and 28 inFigure 5. Due to the 1 spacing of the electrodes 22 and 22 and theelectrodes 23 and 23' the field in the center of the mass is of a verynegligible intensity, the treatment being concentrated adjacent theouter portions of the body ID. The circle indicated at 3|? marks anapproximate boundary between the zone of intensetreatment and thecentral zone of the negligible treatment by the electrostatic field;this circle 30 being approximately tangent to the line indicating theinnermost boundary of the respective fields 21 and 28. It will thus bereadily'apparent how the arrangement shown in Figure 5 will produce aneffect illustrated in the diagramof'Figure 2. Obviously, either pair ofelectrodes could be omitted, but the treatment would be only one-half asefiective for a given length of time. e

The diagram shown in Figure 3 of the drawings suggests an article ormassill in which the dielectric body H is treated most intensely within thecentral zone l8 and to a less extent in the outer annular zone l9.Assuming a central core l2, as illustrated, the diagram may represent anelectrical conductor in which the insulation is vulcanized adjacent thecore so as to secure a strong adhesion between the contacting surfaces.Other examples of the use of such an article or mass will readily occurto the operator skilled in the art.

The arrangement shown in Figure Got the drawings illustrates one way ofattaining the result shown in Figure 3. In this case the mass It) isrotated between the electrodes 32 and 33 of opposite instantaneouspolarity, being connected by means of leads 34 and 35 to theterminals ofa source of high frequency current such as at l5 of Figure 4. Theseelectrodes 32 and 33 are preferably of arcuate shape convex with respectto the mass Ill and are of a width equal to the diameter of the circle31 indicating the approximate boundary between the intensely treatedcentral zone less intensely treated annular outer zone. It will be seenthat during the rotation of the mass III the area within the circle 31corresponding to the zone I8 of Figure 3 will always be within theelectrostatic field 40 while the zone outside of the circle 31 will onlybe intermittently treated as this portion of the mass passessuccessively through the field.

In Figures 7 and 8 of the drawings there is illustrated an embodiment ofthe invention wherein the electrodes are stationary as in the casesshown in Figures 4, 5, and 6 but the arrangement of successive series ofelectrodes is such that the mass I 0' to be treated may be drawnlongitudinally through the space between the electrodes and receive aselective treatment such as illustrated in Figure 2 of the drawings andpreviously described in connection with the means shown in Figure 5. P11this embodiment of the invention, the arrangement of the electrodes atone station-for example adjacent the section line 8A-8A-is exactly thesame as the arrangement shown in Figure 5, and this is illustrated inthe portion 8A of Figure 8. The electrodes 22 and 23 establish anelectrostatic field 27 extending across a segment of the mass l0 and thefield 28 established between the electrodes 22' and 23' similarly treatan opposite segment. The chords marking the inner boundaries of thefields 2.1 and 28 are tangent to the circle 30. At the next treatingstation adjacent to line 8B--BB of Figure 7 the respective pairs ofelectrodes 22 and 23, and 22' and 23' are advanced around the peripheryof the mass it! to an appropriate extent depending upon the number ofstations at which these series of electrodes are located. Assuming fourstations the elec-. trodes will be advanced approximately 45. If thereare more stations contemplated the electrodes need not be advanced tosuch a great extent and furthermore the treatment would be much morerapidly efiected and the mass l0 could travel through the treating zonesat a greater speed. The chords bounding the inner edges of theelectrostatic fields 21 and 28 in all cases are approximately-tangent tothe theoret ical circle 30. In Figures and 8D the electrodes areadvanced still further and the same relative arrangement of fieldsmaintains. Of course, the series of electrodes .22 and 22 areappropriately connected to one terminal of a source of high frequencycurrent by means of the conductors 2'4 and the opposite electrodes 23and 23' are connected by means of the conducing efiect shown in Figure 2of the drawings.

Another means for attaining the outer peripheral or skin treatment of amass is shown in Figures 9 and 10 of the drawings. In this case the mass10', arrangedif desiredwith core 12, is

drawn through successive rings or annualar elecelectrostatic dischargebetween respective electrodes 42 and 43 which are of oppositeinstantaneous polarity forms a field such as indicated by the lines 48in Figure 9, and as the mass is drawn through the electrodes a zone oftreatment such as indicated at 50 in Figure 10 results.

Still another mode of attaining an outerannular treated zone within amass such as H) is shown in Figures 11 and 12 of the drawings. In thisembodiment two helically formed strap-like electrodes 52 and 53 arearranged to form a cage through which the mass l0 may be drawn. Theelectrodes 52 and 53 are respectively connected to opposite terminals ofa source of high frequency current by means of the conductors 54 and 55and an electrostatic field such as indicated at 58 is set up betweenadjacent windings of the electrodes. This results in the production of atreated outer annular zone 50 as shown in A projection of thearrangement-suggested in.

Figure 6 of the drawings for obtaining an efiect such as showndiagrammatically in Figure,3 is illustrated in Figure 13. In this. casesuccessive series of spirally displaced pairs of electrodes are arrangedsimilar to the stations shown in Figure 7 of the drawings; however, inthis case the aim is to treat the ,central portion of the mass I0 moreintensely than the outer annular portion. For this purpose theelectrodes 32 and 3-3 at the first station shown in the portion l3A ofFigure 13 are disposed exactly as in the case of Figure 6. At the nextstation illustrated diagrammatically in subordinate Figure 13B theelectrodes are displaced circumferentially an an gular distance ofapproximately45". In Figures 130 and 13D the electrodes at successivestations are displaced similarly so that a thorough distribution of thefield 40 from various angles may be obtained. The bounding chords of thefields 40 are tangent to a circle indicated at 31 which marks theapproximate boundary between the inner intensely treated zone and theouter less strongly treated part.

In Figures 14 and 15, there is illustrated a still different efiect andmeans by which it may be obtained. The zone of most intense treatment,in this case; designated I9A is intermediate the central part [8A of themass I0 and an outer marginal portion 193 of less intense treatment.

This treatment is efiected by one or more pairs of electrodes arrangedas at 22A and 23A in Figure 15, the eflective width of the electrodesbeing less than a radius of the mass and disposed so that the margins ofthe field 21A are respectively tangent to the circles 30A and 3133approximately bounding the zone HA.

To attain a pattern Tof electrostatic heat treatment as diagrammaticallyshown in Figure 2, instead of rotating the mass Ill as in thearrangement shown in Figure 5 this mass may be held stationary and thecage or frame of electrodes 22A, 22B, 23A, and 23B (Figure 16) maybe'rotated around the mass. The electrodes are carried by an annularring support 55 about which a driving belt 56 may be trained, this beltbeing driven from a pulley 51 carried upon a drive shaft 58 rotated froma suitable source of power. The electrodes of the respective pairs areconnected 'to the appropriate terminals of the source of high frequencycurrent in a manner well known in the art.

A similar arrangement of rotating electrodes for obtaining emphasis oftreatment upon a circular zone is shown in Figure 17 of the drawings inwhich the electrodes 32A and 33A are carried by a ring 65 which isrotated by a belt drive arrangement 66 similar to that shown in Figure16. The electrodes are appropriately connected to a suitable source ofhigh frequency current by any suitable conventional means.

In Figures 18 and 19 there is shown means for treating articles ofvarious configurations by a series of moving electrodes all of which areconnected with one terminal of a high frequency source, an electrode ofopposite instantaneous polarity providing a rest for the articles, Thislatter electrode is indicated at Ill in Figure 18 and is connected to anappropriate terminal by the conductor 1 l, The articles I rest upon theelectrodes 10 and are disposed directly beneath the traveling belt 13which is trained about the rollers M and'l5, this belt carrying a seriesof transversely extending electrodes 16 which are all of oppositeinstantaneous polarity to the electrode 10. The axle 18 of the roller I4is in electrical communication with the electrodes H5 and is connectedthrough the brush contact 19 and the conductor 89 with the otherterminal of the source of current. Figure 19 is a fragmentary plan viewof part of the arrangement shown in Figure 18. The underlying electrodebeing indicated at 10, the articles to be treated at I00, and one of thetransverse moving electrodes I6 being shown moving in the direction ofthe arrows 85. The articles I00 may rest in fixed position on theelectrode 10 or they may be moved at varying speeds in either directionthereon depending upon the nature of the treatment desired, and theduration and intensity thereof.

The high frequency source indicated generally at l5 in Figure 4 of thedrawings and referred to in connection with the other figures, may be ofany suitable form. One conventional oscillator circuit for this purposeis diagrammatically illustrated in Figure 20 of the drawings. Thisarrangement includes a vacuum tube triode having its cathode 90connected to the negative side B of a suitable high potential directcurrent source.

The plate 9| of the triode is connected through.

the radio frequency choke 92 to the positive side B+ of the directcurrent source; The tank coil 93 is connected at one end through theblocking condenser 94 to the plate 9| and is connected at its other endto the cathode 90 and to ground.

The conductors leading to the treating electrodes are indicated at l6and II.

The oscillator is operated at a frequency which may for example be ofthe order of 20 megacycles and acts to produce the electrostatic fieldsbetween the opposed electrodes shown in the other figures of drawingsillustrating the various em bod iments of the invention.

The term axis of the electrodes" as used in the claims refers to thebisector of the angle between the lines passing through the center ofeach electrode of one pair and the axis of the mass of material whereboth of the electrodes of one pair are disposed on the same side of adiameter. Where the electrodes of a pair are centered on a diameter, asfor instance in Figure 13, the term axis of the electrodes refers to theline passing through the center of the electrodes and the center of themass.

Although certain examples and embodiments of the present invention inits various aspects have been illustrated and described herein, theinvention is not to be considered as limited thereto but is susceptibleof various changes and modifications in. structure and procedure and inthe nature of the masses, materials, or articles treated withoutdeparting from the scope of the invention as defined in the followingclaims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. In a device for the electrostatic treatment of a non-metallicdielectric mass which is symmetrical about a' longitudinal axis, asource of high frequency alternating current, electrodes adapted to bedisposed externally of said mass and spaced apart and disposed onopposite sides of a diameter of said mass, means connecting saidelectrodes with said source so that the oppositely disposed electrodesare of opposite instantaneous polarity so as to create an electrostaticfield between them, means for effecting relative rotational movementbetween said mass and said electrodes about said axis, the projectionsof said electrodes on said diameter extending from a point spaced fromthe periphery of said mass to a point spaced from the axis of said mass,whereby during relative rotational movement an intermediate annular zoneof said mass is given a more intense treatment than either the centralor peripheral zones.

2. In a device for the electrostatic treatment of a dielectric masswhich is substantially symmetrical about a longitudinal axis, a sourceof high frequency alternating current, a series of pairs of electrodesadapted to be disposed externally of said mass and successively alongsaid axis, the electrodes of each pair being connected to said source soas to be of opposite instantaneous polarity to create an electrostaticfield between them, and disposed on opposite sides of a diameter of saidmass so that the projection of the widths of said electrodes on saiddiameter is less than said diameter, the axes of said successive pairsof electrodes being angularly displaced about said axis of said masswith respect to the preceding pair, and means formo'ving said mass alongits axis, Whereby'an annular zone of said mass symmetrical about itsaxis is more intensely treated by said electrostatic field than otherportions of said mass.

3. In a device for the electrostatic treatment of a dielectric masswhich is substantially symmetrical about a longitudinal axis, a sourceof high frequency alternating current, a series of pairs of electrodesadapted to be disposed externally of said mass and successively alongsaid axis, the electrodes of each pair being connected to said source soas to be of opposite instantaneous polarity to create an electrostaticfield between them, and disposed on opposite sides of a diameter of saidmass so that the projection of the widths of said electrodes on saiddiameter is less than said diameter and touches the periphery of themass, the axes of said successive pairs of electrodes being angularlydisplaced about said axis of said mass with respect to the precedingpair, and means for moving said mass along its axis whereby an annularouter zone of said mass symmetrical about its axis is more intenselytreated by said electrostatic field than other portions of said mass.

4. In a device for the electrostatic treatment of a dielectric masswhich is substantially symmetrical about a longitudinal axis, a sourceof high frequency alternating current, a series of pairs of electrodesadapted to be disposed externally of said mass and successively alongsaid axis, the electrodes of each pair being connected to said source soas to be of opposite instan taneous polarity to create an electrostaticfield between them, and disposed on opposite sides of a diameter of saidmass so that the projection of the widths of said electrodes on saiddiameter is less than said diameter and touches the axis of said mass,the axes of said successive pairs of electrodes being displaced aboutsaid axis of said mass through an angle with respect to each precedingpair, and means for moving said mass along its axis, whereby an annularcentral zone of said mass symmetrical about its axis is more intenselytreated by said electrostatic field than .another annular zone of saidmass.

5. In a device for the electrostatic treatment of a dielectric masswhich is substantially symmetrical about a longitudinal axis, a sourceof high frequency alternating current, a helical electrode surroundingsaid mass and connected to one terminal of said high frequency source,another helical electrode substantially identical in shape and size withsaid first named electrode, surrounding said mass and intermeshed withsaid first named electrode so that its windings are uniformly spacedalong the surface of said mass from the adjacent windings of said firstnamed helical electrode, whereby-an electrostatic field is set upbetween said windings which traverses the adjacent outer peripheralportion of. said mass, and means for moving said mass through saidhelical electrodes so that the entire outer peripheral zone of said massis treated.

6. In a device for the electrostatic treatment of a mass which issubstantially symmetrical about a longitudinal axis, a source of highfrequency alternating current, a pair of electrodes adapted to bedisposed externally of said mass and connected with said source so as tobe of opposite instantaneous polarity, said pair of electrodes beingdisposed upon one side of a diameter of said mass and the electrodes ofsaid pair being spaced apart on opposite sides of a radius of said masswhich is perpendicular to said diameter, a series of additional pairs ofelectrodes adapted to be disposed externally of and along said mass andsimilarly arranged relative thereof but the axis of each successive pairbeing angularly displaced about said axis of said mass from the nextpreceding one, means for efiecting relative longitudinal movement ofsaid mass and said pairs of electrodes whereby an annular zone of saidmass symmetrical about said axis of said mass is more intensely treatedthan other portions thereof.

7. A method of treating a mass of material capable of having itsphysical or chemical characteristics altered by a high frequencyelectrical field, said material being symmetrical about anaxis,comprising the steps of arranging a pair of electrodes externallyof and adjacent to said mass and connected to the opposite sides of asource of high frequency electrical energy to thereby create anelectrostatic field therebetween, said electrodes being so arrangedadjacent said mass of material that the predominant part of saidelectrostatic field traverses only a selected fractional cross-sectional'area of said material,

and causing such relative movement between said electrodes and the axisof said mass of material as to effect a selective treatment of aselected annular zone of said material symmetrical about said axis.

.8. A method of treating a mass of material capable of having itsphysical or chemical characteristics altered by the influence of a highfretrodes and the axis of said mass to effect diflerential treatment ofdifferent concentric annular zones of said mass symmetrical with saidaxis.

9. A method of treating a mass of material ca pable of having itsphysical or chemical characteristics altered by the influence of ahigh-frequency electrical field said material being symmetrical about anaxis, comprising the steps of positioning a pair of electrodesexternally of but adjacent said material, said electrodes beingconnectedto the opposite sides of a source of high frequenc electricalenergy and so disposed with respect to said mass that the projection ofthe intervening electrostatic field between said electrodes is less thanhalf the transverse dimension of. said mass of material, and causingrelative rotational movment between said electrodes and said materialabout said axis to produce substantially uniform treatment throughout aselected annular zone of said material symmetrical about said axis whichis different from the treatment i of an adjacent annular symmetricalzone.

10. The method asset forth in claim 8 in which the step of positioningthe electrodes includes the disposition of the electrodes in such mannerthat the intervening electrostatic field between said electrodestraverses said mass of material in a direction parallel to the axis ofsaid mass and the relative movement is translatory and parallel tosaidaxis.

11. The method as set forth in claim 8 in which the step of positioningthe electrodes includes the disposition of the electrodes in such mannerthat the intervening electrostatic field between said electrodestraverses said mass of material in a direction substantially transverseof the axis of said mass and the relative movement is translatory andparallel to said axis.

12. The method as set forth in claim 8 in which the step of positioningthe electrodes includes the disposition of the electrodes insuch mannerthat the intervening electrostatic field between said electrodestraverses said mass of material in a direction substantially transverseof the axis of said mass and the relative -movement is rotational aboptsaid axis.

13. A method of treating a mass of material capable of having itsphysical and chemical characteristics altered by a high frequencyelectrical field, said material being symmetrical about an axis, saidmethod comprising the steps of arranging a series of pairs of electrodesconnected to the opposite sides of a source of high frequency electricalenergy and disposed externally of, adjacent and along said mass with theaxes of the successive pair of said electrodes being angularly displacedabout the axis of said mass from the axis of the next preceding pair,said electrodes being so disposed relative to said mass that theintervening electrostatic field between said electrodes traverses only aselected cross-sectional annular zone of said material, and causing suchrelative movement between said electrodes and the axis of said mass ofmaterial as to effect a selective treatment of a selected annular zoneof said material symmetrical about said axis.

14. A method of treating a mass of material capable of having itsphysical or chemical characteristics altered by a high frequencyelectrical field, said material being symmetrical about an axis,comprising the steps of arranging electrodes externally of and adjacentto said mass and con- .nected to the opposite sides of a source of highfrequency electrical energy to thereby create an electrostatic fieldtherebetween; said electrodes being so arranged adjacent said mass ofmaterial that the predominant part of the electrostatic field created byall the electrodes traverses only a selected fractional cross-sectionalannular zone of said material symmetrical about said axis, and causingsuch relative translatory movement between said electrodes and the axisof said mass of material as to effect 'a selective treatment of aselected annular Zone of said material symmetrical about said axis.

H. H. oronvan GRELL HARRY W. RICHARDS,

